Seven weeks into its limited US release, Danny Boyle's Slumdog Millionaire is maintaining the promise it showed at several film festivals - notably Telluride, where it was an audience favourite - that it might be the dark horse of the year, and a film to watch out for in award season. Slumdog has earned about $20m (£14m) so far, which is the level of an independent hit, but its weekly numbers are improving even as word of mouth struggles to convey the astonishing originality of the picture. People say, "Well, it's like the first western Bollywood picture you ever saw!" or, "Look, it's Danny Boyle. You never know what that means. So give it a try!"

Bollywood is a weird, surreal moon lighting up the dark skies of world cinema. For several years, the movie world at large has had to face the prospect of fewer pictures, fewer of lasting quality and a dread that maybe the excitement has gone. Against that there is this enchanted light of Bollywood - is it artificial, fake and crazy, or is it a new light? - representing a culture where film is seething with life, colour, music, silliness, romance, heroes and heroines, and generating a fantastic audience response. Is it just that India is behind the times, as it were, or might it have left us loitering? Case in point: in a season of moribund and stately/pretentious big pictures from America (Benjamin Button, Doubt, Revolutionary Road - all likely to feature in the Oscars race), nothing can match the furious energy and vivacity of Slumdog Millionaire.

You have never seen a film like this. Yet as you see it, you realise the knock-out welcoming embrace Boyle is giving to so many other levels in our culture. As Scott Foundas of the Village Voice said: "It's Dickens with rupees." His point is not just that this 21st-century movie reclaims the narrative fecundity of Dickens, or even that it bumps that concentration over to the wretched/bejewelled world of Mumbai. It's more that here is a film about money, which leads to this prediction: in the next few years, no subject is going to dominate our popular culture more than money.

And there, I hope, you see the running momentum in Danny Boyle's "vivacity" (a word of his choosing, and a measure of his assurance that all movies really need is the force, the chutzpah, the charm and the cheek that can scatter disbelief to the winds). Twelve years ago, in Trainspotting, Boyle saw that drugs were the essential lubrication of the moment, and he made one of the few films that plays fair by both the exhilaration and the terror in drugs. Slumdog Millionaire has the same grasp on the insane way money has shattered our reality but commanded our dreams.

In the years since he came to our attention with Shallow Grave and Trainspotting, Boyle has faltered sometimes. The Beach is not lively enough, though it saw the point of that alluring modern myth of a sweet beach that kids could use as a defence against the drab world; 28 Days Later was monotonously grim, but it was a piercing fable on disaster coming; and Sunshine (for me) took Boyle into a moviescape that relied too much on art direction. He is most himself when he is twisting reality until you see it afresh, and that's what makes Slumdog Millionaire.

I think it's the most audacious cross-over film of the year. I'd give it prizes. The Academy, I suspect, cannot stomach it. But of this I'm certain: play it in a few years' time, from the point of view of economic ground zero, and it will seem like the most prescient movie of this moment. If you want a real thrill, play it with Marcel L'Herbier's L'Argent (1928), just out on DVD. It was made on the brink of the great crash of 1929 - a time when crashes were crashes, not just the frenzy of reality games spinning out of control and into dreamland.